Tropical Storm AMANDA (Text)

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TROPICAL STORM AMANDA DISCUSSION NUMBER 22
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012014
800 PM PDT TUE MAY 27 2014
Amanda's cloud pattern continues to lose organization. Several
microwave overpasses during the past 6 to 8 hours show that the
center of the cyclone is exposed to the south of the nearest deep
convection and is located farther south than previous estimated.
Late-afternoon visible imagery confirmed these findings, with
geostationary imagery also showing the convection warming and
shrinking in coverage. The degradation in organization has resulted
in a significant decrease of satellite intensity estimates since
this afternoon. The initial intensity is somewhat uncertain since
the Dvorak technique does not work well for rapidly weakening
cyclones but is reduced to 60 kt based on a blend of T- and CI
numbers from TAFB and NESDIS SAB. Additional weakening is likely as
south-southwesterly shear, the entrainment of drier and more stable
air, and a cooler ocean surface take their toll on Amanda. Even
though the shear is forecast to decrease in 24 to 36 hours, it
appears that it will be too late for the cyclone to overcome the
combined effect of these negative factors for intensification.
Remnant low status is now forecast in 72 hours, although it could
occur sooner. The official forecast is lower relative to the
previous one and near but a bit lower than a combination of the
multi-model consensus, Decay-SHIPS, and LGEM.
Center fixes suggest that the motion had been west-northwesterly
throughout the day, and the initial motion estimate is left of
the previous one or 305 degrees at 3 kt. The cyclone remains
embedded in a weak steering environment between a low- to mid-level
ridge to the east-northeast and a mid- to upper-level trough to the
northwest. This synoptic pattern should allow for a generally slow
northward or north-northeastward motion for the next few days before
Amanda degenerates into a remnant low and turns westward or
southwestward. Should Amanda weaken faster than forecast, little
motion is expected, and its remnants could turn eastward in an
anomalous low-level westerly flow. The official forecast is on the
far western side of the guidance envelope, and is much slower than
the previous forecast due primarily to the more southern initial
position.
FORECAST POSITIONS AND MAX WINDS
INIT 28/0300Z 14.6N 112.9W 60 KT 70 MPH
12H 28/1200Z 15.0N 112.8W 50 KT 60 MPH
24H 29/0000Z 15.8N 112.4W 40 KT 45 MPH
36H 29/1200Z 16.5N 111.9W 35 KT 40 MPH
48H 30/0000Z 17.0N 111.5W 30 KT 35 MPH
72H 31/0000Z 17.1N 111.4W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 01/0000Z 16.8N 111.5W 15 KT 15 MPH...POST-TROP/REMNT LOW
120H 02/0000Z 16.5N 111.8W 15 KT 15 MPH...POST-TROP/REMNT LOW
$$
Forecaster Kimberlain
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